Packaged explosive product



May 9, 1967 Filed June 23,

TANK

EXTRUSION DEVICE G. L. GRIFFITH 3,318,242

PACKAGED EXPOS I VE PRODUCT 3 Sheets-Sheet 1 May 1967 G. GRIFFITH 3,318,242

PACKAGED EXPOS I VE' PRODUCT Filed June 23, 1965 3 Sheets-Sheet 2 FIG 4 May 9, 1967 c. L. GRIFFITH PACKAGED EXPOSIVE PRODUCT 3 Sheets-Sheet 5 Filed June 23, 1965 FIG. 6

nited States Patent 3,313,242 PACKAGED EXPLOSKVE PRODUCT George L. Grifiith, Coopersburg, Pa., assignor to Trojan Powder Company, Allentown, Pin, a corporation Filed June 23, 1965, Ser. No. 466,158 13 Claims. (Cl. 10224) This application is a continuation in part of co-pending application of Ser. No. 177,583, filed Mar. 5, 1962, now U.S. Patent No. 3,216,307.

This invention relates to a packaged explosive product, and more particularly to a flexible continuous length of packaged explosive, comprising a continuous column of explosive composition, a wrapper of flexible sheet material, continuous for substantially the entire length of the package, folded over the continuous column in close contact therewith in a manner to completly enclose and package the column within the folded sheet; and a reinforcing wind of filamentary material tightly wound about the package in a manner to hold the longitudinal seam closed and retain the explosive column within the package, and to impart flexibility thereto, due to the tightness of the winding.

The explosives industry customarily has packaged explosive compositions in individual containers, which are filled with explosive, usually in the form of a dry powder I or slurry, and then closed. Such a packaging procedure requires a large, costly, inefficient plant. It is necessary to roll the explosive shell containers in a shell rolling house, after which the empty shells are sent to a punch house where they are filled in a loading or punching machine, either manually or mechanically. The shells are loaded at one station of the machine, crimped at the second station, and expelled for packing at the third station. This procedure is essentially a batch procedure, and it has been impossible to mechanize this such that packaging could be carried out in a completely continous operation, starting with the formation of the shell and ending with a filled, closed package.

Recently, machinery has been made available which preforms an explosive composition, and this is then wrapped automatically in paper and crimped at both ends, to produce a completed shell rather quickly as compared to the conventional procedure. This, however, is also an intermittent operation, which produces shells of a fixed length. Due to certain mechanical restrictions, as well as the investment cost of the machine, it is not feasible to manufacture finished shells having a length in excess of sixteen inches. Furthermore, the production rate of the machine is rather low, and the finished explosive package requires multiple paper wrappings to lend it sufficient strength to withstand handling and packaging. Paper is costly, and the use of an unusually large amount of paper is undesirable, since paper produces unfavorable fume characteristics when the explosive is detonated.

The authoritative Swedish text, Nitroglycerin Och Dynamit, by Nauckhoif and Bergstrom, published in 1959, summarizes the history of explosives manufacture and packaging. However, no example is given in the book of the continuous packaging of a finished explosive.

The packaging of ammonium nitrate explosives presents a particularly severe problem, from the standpoint of economics. Ammonium nitrate is a cheap raw explosive material, which can be sensitized rather inexpensively with fuel oil or some other form of carbon or carbonaceous material to form what are termed the nitrocarbonitrates, which have explosive properties. Such mixtures can be brought in bulk to the explosive site where they can be filled directly into small diameter bore holes having a diameter of as low as one inch, and then shot. This technique poses a particularly diificult pack- 3,3l8,2l2 Patented May 9, 1967 aging problem, since, using conventional explosive packaging procedures, it has been practically impossible to package an inexpensive product in a practical manner at a price sufficiently low to be competitive with the ammonium nitrate-fuel oil bulk compositions which can be blown directly into the holes without packaging.

A further problem created by individual packaging of explosive compositions arises from the necessity of propagating the charge from one cartridge to another in the train. It has always been necessary to use an explosive composition in the package of such sensitivity that it is capable of shooting through a discontinued column of explosive, the discontinuity being brought about by the fact that for practical purposes explosives are loaded normally in lengths of less than 24 inches, and usually in lengths of 4 to 8 inches. Thus, an explosive column in a small diameter hole of great length usually consists of four to twelve sticks of powder, and the composition must necessarily have sufiicient sensitivity so that the detonating wave will not die out as it travels through the discontinuous column of a plurality of sticks. Furthermore, a discontinuous column has less water resistance, since the point where two shells butt together is the first point at which water desensitizes the composition, presenting a zone through which the shock wave often fails to pass from one cartridge to the next. Obviously, if it were possible to prepare an explosive column of great length, so that a continous column could be loaded in the hole in place of a discontinuous one, composed of a plurality of sticks in close juxtaposition, it would be possible to use an explosives composition of less sensitivity, since there would be no need to propagate the explosive wave from one cartridge to another. Such a column would also have greater water resistance than the discontinuous one, since there would be no point at which water could enter between one portion of the explosive and another.

The packaging of Water slurry or water gel explosives has also presented a problem. These are difiicult to package in an efficient manner so that they can be sold at a price which is competitive to ammonium nitrate-fuel oil compositions. These difficulties basically are due to the lack of a method for packing long continuous tubes in an economical manner.

Casings of any desired length can be fabricated from plastic materials, such as regenerated cellulose, polyethylene, polypropylene, and the like. These are extruded in the desired diameter, and then filled by means of a long loading tube through which the filling material is extruded into the casing. This method has been used for many years in the manufacture of sausages in the meat industry. However, it is not adapted for explosive compositions. It is quite difficult by this method to load a one inch diameter or smaller casing four feet or more in length, where the casing has to be pushed over a loading tube and then loaded under relatively high extrusion pressures. Unless the material being extruded is completely free of occluded air, there is a tendency for air pockets to form in the column of explosive. Any air pocket cuts off the detonating wave in the powder. In addition, it is necessary to use extremely light gauge casing to avoid imparting unfavorable fume characteristics to the finished product. A larger amount of casing material such as would be present in a thick casing causes the formation of large quantities of carbon monoxide as well as carbon dioxide, both of which are poisonous, and dangerous when present in underground working. If the casing material is not manufactured with great care, it will possess portions of uneven diameter, both thick and thin, as well as pin holes. Pressure from the extruded explosive is unevenly distributed along the length of the tube, causing the tube to swell at the thin spots, and to be thinner at the thick spots. This results in an explosive package of nonconstant diameter which leads to difficulties in the field. Furthermore, if there is only an extremely thin coating of plastic material to protect the enclosure, there is a chance for the casing enclosure to rupture and lose its contents during loading or shipping. Very thin spots also result in a low support for the cartridge, and the finished sticks are flimsy and limp, so that difiiculty is encountered when these are to be loaded into conventional holes filled with rock which may have rough corners and surfaces.

In accordance with the instant invention, explosive compositions are packaged by extruding the compositions in a column of the desired configuration and length while forming an explosive package about and enclosing the extruded column of explosive. The extruded column is brought into contact with the enclosing wrapper shortly after leaving the extruder, and through frictional engagement therewith draws with it the wrapper and the sheet of wrapping material. Upon continued outward movement of the wrapper with the extruded column, the wrapping material is caused to form an envelope about the column, thereby enclosing it in a package of wrapping material. Preferably, the wrapping material is folded lengthwise over a forming mandrel, such as over the extrusion tube or nozzle, using a wrapping sheet of such width as to completely enclose the extruded column plus a small overlap to strengthen the longitudinal seam where the two edges of the wrapper join. Pressure is applied to the surface of the package sufficient to retain the explosive therewithin, and prevent distortion of the package under the pressure of extrusion. The lapped edges of the wrapper are closed and perfectly sealed.

The pressure necessary to hold the seam together before sealing can be applied to the package by any of several means. T he open seam between the edge or fold of the Wrapper can be glued promptly after forming. The Wrapped package also can be retained between vanes or a series of circular rolling surfaces. One simple and preferable method is to encircle the package with two sets of opposed spiral winds of filamentary material, such as string, cord, or wire, one set being wound clockwise and the other counterclockwise about the package. Such retaining filaments can be applied by conventional means which are well known to those skilled in the packaging art, and those means form no part of the instant invention.

The filaments can be wound in a single spiral wind or preferably in opposed spiral winds, one being wound clockwise and the other counterclockwise about the package. This opposed spiral winding may be seen to best advantage by reference to FIGURE 5. The windings, however, may also encircle the package at right angles to the seam. These windings may be of a continuous length of filamentary material and therefore connected or, they may encircle the package as individual winds of filamentary material, and be disconnected. These windings may be applied by conventional means well known to those skilled in the packaging art. A continuous winding may be seen to best advantage in FIGURE 6. A discontinuous winding may best be seen by reference to FIGURE 7. Such filaments can, if desired, be bonded to the package by application of the same means used to bond the seam. Any desired length of package can be obtained by measuring and cutting off an appropriate length of column.

The package, without the windings of the filamentary material, can be somewhat rigid. This result is due to the tight packing of the explosive composition within the wrapper. It is desirable that the packaged explosive product be flexible, due to the fact that it must be inserted into long blast holes which are neither smooth nor straight. To impart the attribute of flexibility to the explosive product, the filamentary material is wound tightly about the package. The pressure exerted in the package by the windings causes indentations and convolutions in the wrapping material, and the explosive compositions therein. These indentations and convolutions are permanently maintained in the package by the tightness of the windings. The combination of the windings of filamentary material, the indentations, and the convolutions, produce a hinge effect, and allow the package to flex at all points that are directly beneath the windings. Such a package can be inserted easily into an uneven or curved blast hole.

The retaining filaments are preferably of a material such as glass fibers which do not result in generation of an appreciable quantity of fumes when the package is exploded. The filaments may also be made of any material capable of being tightly wound around the package, and due to the tightness of the winding, imparting flexibility thereto, such as synthetic plastic, i.e. nylon, Dacron (ethylene glycol esters of terephthalic acid), Orlon (polyacrylonitriie), polypropylene, or metal, hemp, jute, cotton, sisal or other filamentary materials.

The wrapping material may have a tendency to wrap itself spirally about the loading mandrel under packing conditions. This spiraling tendency can be counterbalanced by an opposite force sufficient to restrain it. This counterbalancing force can be applied by means of a belt or other means which slips over the package and tends to wind the package in a direction opposite to that of the spiraling tendency of the wrap. The application of a filament wound about the package in the direction opposite to the spiraling also is effective. While one filament wind to counterbalance the tendency of the paper strip to wrap itself about the loading mandrel is usually adequate, a double wind in both directions gives a far greater and more satisfactory strength to the package.

The open seams of the wrapper can be bonded by any desired means appropriate to the wrapper material used. A bonding agent or composition can be applied, or the overlapped edges can be sealed by application of heat and pressure or solvent and pressure. The entire package can be coated with a surfacing material, if desired, to add greater strength and resistance to abrasion to the package, and this coating material will at the same time cover over and seal any open seams. Thus, for example, paper can be bonded by application of glue or wax through spraying or brushing of the package, or by application of kissing rolls, or by passing the package over a continuous surface or film of the bonding material. Thermoplastic synthetic resinous materials such as polyvinyl chloride or polyethylene can be sealed by application of heat and pressure or by application of a solvent for the resin and pressure, removing the solvent by heat- It is apparent from the above description that by this method it is quite unnecessary to form, separately, empty containers which then must be filled with explosive composition. The wrapper or package can be formed continuously with the extrusion of the explosive composition, and the method is accordingly appropriate to package any explosive composition which can be extruded. Such compositions range from dry powders to plastic semi-solid explosive compositions which have sufiicient rigidity to retain the extruded configuration until enclosed with wrapper material.

The method makes it possible to employ plastic materials, such as polyvinyl chloride, polyethylene, and polypropylene, for the packaging material, because the method eliminates the possibility of trapping air pockets in the package. Any air which may be extruded with the explosive composition Will leak rapidly from the shell through the open seam or seams along the extrusion nipple, and the extruded column will move forward, drawing the wrapper material with it, only when explosive material is being pushed forward. Where there is an air pocket, there is no explosive mass to apply force, and hence, there is no further movement of the extruded explosive until the air pocket has been eliminated. The wrapper material may also be made of paper, metal foil,

cloth, or any other material which may be folded as a continuous wrapper about the column of explosive material thereby forming an elongated continuous explosive package.

The extruded package can be handled in any manner known to the art. Very long and continuous columns can be prepared by winding the extruded package on a spool or roll. Columns may be packaged to any desired length by cutting them ofi, either automatically or manually, at the desired length. The exposed ends can be protected or closed off by spraying, dipping, applying caps, or other well known packaging methods. In many cases it is unnecessary to protect the ends, since the finished explosive columns can be shipped in cases which are themselves closed, and thereby prevent atmospheric moisture from entering the package. It is also possible to improve the strength of the outer covering by means of glueing, spraying or continuous dipping. All such procedures are well known to those skilled in the explosives and packaging arts.

FIGURE 1 is a plan view of an apparatus for carrying out the invention employing a sheet of wrapping material which is applied lengthwise of the extruded mass of explosive and showing the extruder nozzle, the mandrel about which the wrapper is folded in forming the explosive package, and the mechanism for spirally winding about the package two opposed spirals of filaments to retain the explosive within the package prior to sealing.

FIGURE 2 is a cross-sectional view on an enlarged scale through the apparatus of FIGURE 1, taken along the line 22, and showing one Winder.

FIGURE 3 is a cross-sectional view on an enlarged scale taken along the line 3-3 of FIGURE 1, and showing the other winder.

FIGURE 4 is a view on an enlarged scale and partly in section of the wrapping portion of the apparatus of FIGURE 1, viewed in the opposite direction.

FIGURE 5 is a view on an enlarged scale of a section of a packaged explosive product, showing two filaments wound spirally about the package.

FIGURE 6 is a view on an enlarged scale of a section of packaged explosive product, showing filaments wound at right angles to the seam and tied from a continuous length.

FIGURE 7 is a view on an enlarged scale of a section of packaged explosive product showing tied filaments of discontinuous lengths of filamentary material.

The apparatus shown in FIGURE 1 comprises an extruder 1 equipped with an extrusion nozzle 4 from which the explosive composition emerges in the form of an extruded column 6. Positioned at a point a short distance from the extruder is a folder 3 in the form of a flared herni-cylinder, at the near side end 10 where it first engages the wrapping material having a diameter approximately twice that of the extruder, and at the outside end 11 having a diameter very closely approximating that of the extrusion nozzle. Wrapping material 2, for example, paper, from the storage roll 7 is brought into contact with the flared near side end of the folder, and there folded about the extrusion nozzle 4, and is formed into a tube at the tip of the extrusion nozzle upon the application of strings 8 and 9.

Adjacent the end of the folder and also encircling the extrusion nozzle is a string Winder assembly. Mounted on the winder gear 12 are a storage spool 13 of string and a pair of winder arms 14 and 15, each fitted with eyes 18 and 19 through which string 8 from the spool 13 is passed. Rotation of the string winder gear and accompanying assembly in a clockwise direction draws string from the spool by means of the arms, and the string is thus wound clockwise about the extrusion tube. A second string winder assembly is positioned slightly beyond the first, and also is equipped with a spool 20 and Winder arms 21 and 22, all mounted on winder gear 23. The second string Winder is to be rotated counterclockwise about the tube. The winder assemblies are rotated through fixed gears 24- and 25 operatively connected by the shaft 26 to a driven belt and pulley arrangement 27 operated from the extrusion shaft 28 driven in turn by motor 29.

Beyond the second string winder is positioned a pair of applicator nozzles 40 and 41, which feed bonding composition to the tube package from the reservoir 42. These are in close juxtaposition to the wrapped tube of explosive emerging from the second string winder, one nozzle 40 being directed at the seam thereof. A carrying belt 45 is provided to support the Wrapped explosive package, and apply heat thereto from heater 46 to dry bonding composition applied by the nozzles. Finally, a storage roll 50 receives and winds up sealed packaged explosive 51 emerging from the system.

In operation, explosive composition 6 is extruded through extruder 1. The wrapping material 2 in sheet form is drawn from storage roll 7 to and through the folder 3, where it is folded over the exterior of the extruder nozzle 4, and then brought forward along the outside of the extruder nozzle 4 over the end thereof, at which point it comes into contact with the column 6 of explosive composition emerging from the extruder nozzle. The explosive composition draws the wrapping material with it as it emerges from the extruder, and thus continually feeds a supply of wrapping material 2 from the storage roll 7. Simultaneously, the wrapping material 2 is formed into a hollow tube 5 having sufficient retentive strength to retain the explosive composition therein without distortion through the application of a double opposed wind of strings 8 and 9. The strings 8 and 9 are applied by means of the string winders, the first applying string 8 from the spool 13 clockwise and the other applying string 9 from the spool 20 counterclockwise. The end of the extrusion tube is beyond the point at which the second string is applied, thus furnishing internal support for the tube formed under the pressure of the strings. The strings are bonded to the wrapping material by application of glue or other bonding agents from nozzles 40 and 41, and heated to complete the bond. The finished continuous explosive shell 51 emerges fro-m the system in a continuous length, which can be wound up on a storage roll 51 as shown, and cut in any desired length.

FIGURE 5 is a view of a section of packaged explosive product showing the wrapping material 2, the explosive composition 6 and two filaments 8 and 9 wound spirally about the package.

FIGURE 6 is a view of a section of packaged explosive product, showing the wrapping material 2, the explosive composition 6 and the filament 8 wound at right angles to the seam and tied from a continuous length.

FIGURE 7 is a view of a section of packaged explosive product showing the wrapping material 2, the explosive composition 6 and the filaments 8 wound at right angles to the seam and of discontinuous lengths of filamentary material.

The filamentary material as shown in FIGURES 6 and 7 can be wound by conventional means and their application does not require substantial modification of the entire packing apparatus as described.

The package of FIGURE 7, for example, could be Wrapped by a device similar to that described in US. Patent No. 3,033,102 to Fryklund, dated May 8, 1962. The wrapping could be made of a thermoplastic material, and sealed directly by heat welding as set out by Fryklund, or the wrapping could be of string or twine, and a melted thermoplastic material could be used to connect the two ends of the string.

I claim:

1. A flexible continuous detonable cartridge of packaged detonable explosive, comprising a continuous column of a detonable explosive composition; a wrapper of flexible sheet material, continuous for substantially the entire length of the package, folded substantially parallel to the longitudinal axis of column over the column of detonable explosive into close contact therewith in a man- 7 ner to completely enclose and package the column within the folded sheet, with the folded-over edges thereof abutting each other in a generally longitudinal seam, the detonable explosive column filling substantially all of the volume of the space within the folded sheet, and being substantially uniform in density and free from air pockets; and a reinforcing wind of filamentary material tightly wound about the package in a plurality of spaced apart windings in a manner to hold the longitudinal seam closed, retain the explosive column within the package and impart flexibility to the package due to the spacing and the tightness of the windings.

2. A :packaged explosive in accordance with claim 1 in which the filamentary material is spirally wound about the package.

3. A packaged explosive in accordance with claim 1 having two opposed spiral winds of filamentary material.

4. A packaged explosive product in accordance with claim 1 having a continuous length of filamentary material wound about the package at right angles to the seam.

5. A packaged explosive product in accordance with claim 1 having discontinuous lengths of filamentary material wound about the package at right angles to the seam.

6. A packaged explosive in accordance with claim 1 in which the filamentary material is of glass fibers.

7. A packaged explosive in accordance with claim 1 in which the filamentary material is of synthetic plastic.

8. A packaged explosive in accordance with claim 1 in which the wrapper is of synthetic plastic material.

9. A packaged explosive in accordance with claim 1 in which the wrapper is of polyethylene.

10. A packaged explosive in accordance with claim 1 in which the wrapper is of paper.

11. A packaged explosive in accordance with claim 1 in coiled form.

12. A packaged explosive in accordance with claim 1 in which the longitudinal scam is sealed.

13. A packaged explosive in accordance with claim 1 in which the wrapper has a coating of protective material.

References Cited by the Examiner UNITED STATES PATENTS 399,878 3/1889 Graydon l0298 422,441 3/1890 Peters 102-24 892,757 7/1908 Mosier 10297 1,023,142 4/1912 Ellsworth 10227 1,517,878 12/1924 Wasmayr 578 1,674,773 6/ 1928 Fritzsche 102-27 1,824,141 9/1931 Hill 10224 2,923,239 2/1960 Andrew et a1. 102 27 3,033,102 5/1962 Fryklund 10014 3,049,079 8/ 1962 Eilo 10224 FOREIGN PATENTS 578,853 7/1946 Great Britain.

BENJAMIN A. BORCHELT, Primary Examiner.

ROBERT F. STAHL, Examiner. 

1. A FLEXIBLE CONTINUOUS DETONABLE CARTRIDGE OF PACKAGED DETONABLE EXPLOSIVE, COMPRISING A CONTINUOUS COLUMN OF A DETONABLE EXPLOSIVE COMPOSITION; A WRAPPER OF FLEXIBLE SHEET MATERIAL, CONTINUOUS FOR SUBSTANTIALLY THE ENTIRE LENGTH OF THE PACKAGE, FOLDED SUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXIS OF COLUMN OVER THE COLUMN OF DETONABLE EXPLOSIVE INTO CLOSE CONTACT THEREWITH IN A MANNER TO COMPLETELY ENCLOSE AND PACKAGE THE COLUMN WITHIN THE FOLDED SHEET, WITH THE FOLDED-OVER EDGES THEREOF ABUTTING EACH OTHER IN A GENERALLY LONGITUDINAL SEAM, THE DETONABLE EXPLOSIVE COLUMN FILLING SUBSTANTIALLY ALL OF THE VOLUME OF THE SPACE WITHIN THE FOLDED SHEET, AND BEING SUBSTANTIALLY UNIFORM IN DENSITY AND FREE FROM AIR POCKETS; AND A REINFORCING WIND OF FILAMENTARY MATERIAL TIGHTLY WOUND ABOUT THE PACKAGE IN A PLURALITY OF SPACED APART WINDINGS IN A MANNER TO HOLD THE LONGITUDINAL SEAM CLOSED, RETAIN THE EXPLOSIVE COLUMN WITHIN THE PACKAGE AND IMPART FLEXIBILITY TO THE PACKAGE DUE TO THE SPACING AND THE TIGHTNESS OF THE WINDINGS. 